A variety of diseases exist that require regular treatment by injection of a medicament. Injection devices known in the art include infusion and patch pumps for delivering injections of medicament. Another type of injection device that is gaining traction is a bolus injector device. Biological medicaments are being increasingly developed which comprise higher viscosity injectable liquids and which are to be administered in larger volumes than traditional liquid medicaments. Some bolus injectors are intended to be used with relatively large volumes of medicament, typically at least 1 ml and maybe a few ml. Injection of such large volumes of medicament can take some minutes or even hours. Such high capacity bolus injectors can be called large volume devices (LVDs) and may comprise a pre-filled disposable medicament delivery device or, alternatively, a disposable medicament delivery device into which a patient or medical personnel must insert a medicament cartridge prior to use. To use an injection device such, as an LVD, it is first supported on a suitable injection site of a patient and, once installed, injection is initiated by the patient or another person (a user).
Particularly in the case of patient-operated devices which require insertion of a medicament cartridge prior to use, the drug delivery process from start to finish can be a complicated multi-step process. Steps can include gathering all of the device components, removal of each from their respective packaging, assembly of the components to ready the device for medicament administration before the actual process of injecting the medicament can even begin. Such devices may also require insertion of a battery, a needle assembly and/or other component(s) prior to use of the device. Such processes are therefore complicated for the patient to remember, intrusive upon his or her daily schedule, and increase the risk that the patient may not correctly perform the medicament administration. In addition, a patient may have limited dexterity or other ailments making assembly of the device components difficult.